Field of the Invention
The present invention relates to image processing apparatuses and control methods thereof, and particularly relates to techniques for correcting the brightness and sharpness of an image.
Description of the Related Art
A conventional technique for correcting brightness (“relighting”) by illuminating an object in an image with light from a virtual light source is known (Japanese Patent Laid-Open No. 2010-135996). This technique makes it possible to brighten dark areas such as shadows produced by ambient light, which enables the image to be corrected so that an object present in blocked-out shadows, for example, can be discerned.
In the case of relighting on a facial area, for example, an area having a lower luminance than an average luminance of the overall facial area is extracted as a shadow area and the brightness of the shadow area is increased, and as a result shadows in a facial area can be suppressed without affecting the brightness of other areas.
The method disclosed in Japanese Patent Laid-Open No. 2010-135996 raises the brightness of the shadow area by increasing the gain. However, increasing the gain amplifies noise components in addition to signal components, which causes a drop in the S/N ratio of the corrected area. Japanese Patent Laid-Open No. 2010-135996 does apply a noise reduction filter in order to suppress a drop in the S/N ratio, but the noise reduction process is a smoothing process and can therefore cause a drop in the sharpness of the image.